Packaging asbestos fibers

ABSTRACT

Disclosed is a method of packaging asbestos fibers wherein damp asbestos fibers are consolidated into blocks having a density of at least about 100 lbs./cu. ft. (PCF). These blocks can then be stacked on pallets, pulpable pallets if desired, and secured to said pallet with various means, for example with a shrink film, to produce a clean, compact package. At the point of use, the blocks are disintegrated using a block-breaker and the resultant pieces are then opened into a loose mass of asbestos fibers in a conventional opening apparatus.

This is a Division of application Ser. No. 438,969, filed Feb. 4, 1974.

This invention relates to a novel asbestos package and to a process forpackaging loose asbestos fiber for shipment. More particularly, itrelates to packaging of asbestos fibers in an extremely dense andconvenient form that insures less chance of damage and loss in shipmentand thus more convenience and economy to the shipper, transporter andthe user.

BACKGROUND OF THE INVENTION

Asbestos fiber, after it has been mined and separated from associatednon-asbestos minerals and is ready for shipment, is in the form of afluffy fibrous mass having a density of about 3 to about 20 PCF.Although asbestos can be shipped in this form either in containers or inbulk, in many cases it is desirable to ship the material in a densifiedform to reduce freight and handling costs.

In the past it has been customary to compact asbestos fiber inpressure-packed bags to a density of about 50 PCF. In this packagingtechnique the loose mass of asbestos fibers having a density of about 3to 20 PCF and containing inherent moisture, which normally is less thanabout 1.5% is given a preliminary compaction to about 25 PCF using ascrew conveyor or pug mill to partially de-air and compact the mass. Theresultant 25 PCF material is then fed into a bag or a box under pressureto produce a package of asbestos fiber having a density of about 50 PCF.When these packages of asbestos reach the user, normally the asbestos isremoved from the container and processed by a device which breaks theconsolidated asbestos down into smaller pieces of a size convenient forfurther opening or dispersion in either wet or dry systems such as apulper or fiber opener.

This conventional technique of packaging asbestos fiber has providedconsiderable savings and freight and handling costs as compared with thetechnique of shipping asbestos loose in low density form in containerssuch as bags, boxes, etc. The cost of bags or boxes for the 50 PCFtechnique shipment, however, is still significant. More importantly, ablock density of about 50 PCF is still relatively low compared to thetheoretical density of asbestos fiber which is about 159 PCF.

BRIEF SUMMARY OF THE INVENTON

It has now been discovered that if a liquid, such as water, is added anddispersed throughout the fluffy fibrous mass in a sufficient amount toraise the moisture content of the mass to about 2 to about 8% prior tothe final compression step and if an intermediate compaction step isadded, blocks having a density of at least about 100 PCF can beproduced. These higher density blocks can be shipped without placingthem in a container such as a bag or box. By stacking the blocks onto apallet and securing said blocks thereon with conventional means, such aswith a shrink film, the need for the bags or boxes previously used iseliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the equipment used to produce dense asbestosblocks for shipment.

FIG. 2 is an end view of a set of three movable sections used torestrict the flow of intermediately compacted damp asbestos fiber fromthe intermediate compaction apparatus.

FIG. 3 is a side view of one of the three movable sections showing thesection in a partially open position.

FIG. 4 is a side view of the mold box of the final compaction device orblock press.

FIG. 5 is a side view of a block-breaker used to break up the block atthe point of use as an initial step in reducing the block to a loosemass of asbestos fibers.

FIG. 6 is a partial top view of the block-breaker.

FIG. 7 is a perspective view of a plurality of the dense asbestos blocksfastened onto a pulpable pallet using a layer of shrink film.

DETAILED DESCRIPTION OF THE INVENTION

The system used to package asbestos fiber according to the presentinvention is illustrated in FIG. 1. Loose asbestos fiber 12 ready forpackaging is continuously transferred from storage bin 10 into anauger-type mixer or pug mill 14. Auger 16, driven by drive means 18,rotates producing a mixing and consolidating action and at the same timecauses the asbestos to move through the auger mixer.

Soon after the fluffy asbestos fiber enters mixer 14 it is subjected toa spray of liquid 20 from one or more nozzles 24 connected to a liquidsource or manifold 22. The addition of a liquid to the asbestos fiber iscritical to obtaining a density of at least about 100 PCF in the finalcompaction step. About 2 to 8%, based on the dry weight of the asbestosfiber, of liquid is added at this point. Water is the preferred liquidwith an addition of about 2 to 8% being the most preferred range.Additions of 2-4% are typical, but additions above 4% are oftennecessary to achieve the desired density.

Other liquids, compatible with the user's requirements, could be used aswell as small additions of wetting agents and/or plasticizers. Forexample, in cold weather it might be desirable to use a liquid having avery low freezing point such as a mixture of water and ethylene glycol.

The added liquid is evenly distributed in the fluffy mass of asbestos asthe mixture is agitated and moved through the latter portion of themixer 26. Some compaction or consolidation of the fibrous mass occurs insection 26 of the mixer 14 and therefore the mixer also functions as apreliminary compaction device. Finally, the damp asbestos is dischargedfrom the mixer 14 as auger 16 moves it to opening 27.

Although a continuous auger mixer is illustrated for mixing and forproviding preliminary compaction, other types of mixers, includingbatch-type mixers, could be used for this purpose. For example,continuous or batch-type paddle mixers and V-blenders (with agitators)could be used.

Preliminarily compacted damp asbestos fiber clumps 28 next enterintermediate compaction unit 32 which contains an extrusion auger 34driven by a reducer 36 connected to a moter (not shown) by belt 40 andpulley 38. Auger 34 moves the damp asbestos clumps into the intermediatecompaction chamber 42 where a set of three movable sections 44 restrictthe opening in the end of the chamber. The movable sections providesufficient back pressure on the damp asbestos to produce intermediatelycompacted asbestos fiber clumps 52 having a density of about 25 PCF.

A hydraulic or pneumatic system is connected to cylinders 48 which arepivotally mounted to lever extensions 46 on movable sections 44 using aclevis and a pin 50 so that lever extension 46 can pivot around pin 51(see FIG. 3) to adjust the size of the opening between the movablesections. Changing the position of the movable sections changes the sizeof the opening in the end of compaction chamber 42 (see FIG. 2) and thusadjusts the amount of back pressure asserted against the asbestos fiberin said chamber.

The amount of pressure required in the hydraulic or pneumatic systemwill vary depending upon the size of the cylinders 48, the diameter ofchamber 42, the length of lever 46 and the location along lever 46 ofpin 51. For example, in a system where chamber 42 has an internaldiameter of about 8 13/16 inches, the cylinders for the movable sectionsare 13/4 inch bore, the lever arm distance between pin 50 and pin 51 is2 inches and the lever arm distance between pin 51 and the insidediameter of chamber 42 is about 15/8 inches, a hydraulic or pneumaticsystem pressure of about 20-80 PSI has been found to be a suitableoperating range when auger 34 is rotating at about 100 RPM. The exactlevel of pressure necessary, however, will depend upon the grade andquality of asbestos and the amount and type of liquid present.

The intermediately compacted asbestos fiber clumps 52 are fed intohopper 54 which feeds a weigh-feeder 56 for feeding the desired weightof asbestos fiber into mold chamber 64 to make a block having a densityof at least 100 PCF of a desired size. Any conventional weigh-feeder canbe used for this purpose.

The damp intermediately compacted asbestos fiber clumps are finallycompacted into blocks with press 58. Any type of press normally used toconsolidate loose materials would be suitable. The press illustrated inthe drawings comprises a large hydraulic cylinder 60 mounted to thepress with rods 62. The piston of cylinder 60 is connected to an upperplaten that enters mold box 64, strengthened by ribs 65 and presses thedamp asbestos therein against a stationary bottom platen 68.

Prior to final compaction, the intermediately compacted damp asbestosfiber clumps are relatively low in density and thus each charge ofclumps in mold box 64 contains a substantial amount of air. Much of thisair must be removed prior to or during compaction to allow the block tobe pressed to at least 100 PCF density and to prevent build-up of airpressure within the compacted block during compaction that would crackthe block when the exterior pressure on the block was reduced.

This undesirable air may be removed in several ways. For example, moldbox 64 could be connected to a vacuum de-airing system which could beactivated prior to and/or during pressing to remove the unwanted air. Inthe embodiment illustrated in FIGS. 1 and 4 the air is removed duringpressing by forcing it out through a plurality of slots 66 located inthe wall of mold box 64 by the pressing action. These slots are evenlydistributed around the lower portion of mold box 64 where the finalcompression takes place. The slots should be sufficiently small toadequately support a permeable inner liner 67 (shown in FIG. 4) thatprevents the asbestos fiber from escaping out through slots 66. Atypical width for the slot is about 1 inch with the length varyingbetween about 21/2 to 6 inches.

Mold box 64 contains an inner permeable liner 67 covering the theslotted area. Suitable materials for use as said liner are metallicscreens or perforated metallic thin sheet material having openings ofabout 1/16 of an inch or smaller. Since the purpose of the liner is toprevent the asbestos from being pressed out through slots 66, the sizeof the openings in the liner will vary somewhat depending upon the gradeof asbestos fiber being compressed. The upper platen is sized to providesufficient clearance to accommodate liner 67.

After the block has been finally compressed to the desired density, thepressure is released by reversing the upper platen with cylinder 60. Theblock receiving platen 72 is then raised into a position slightly belowbottom platen 68, using cylinder 74. Bottom platen 68 is then withdrawnhorizontally using cylinder 70 which allows the compressed block to droponto block receiving platen 72. Block receiving platen 72 is thenlowered with cylinder 74 to remove the block from mold box 64. The blockis then removed from platen 72.

Although the dense blocks could be placed in bags or boxes or othercontainers, this is not necessary. The dense blocks are relativelystrong and relatively dust free. The most convenient and economicalpackage is made by merely stacking and securing the blocks on a shipablepallet as shown in FIG. 7. Although any conventional securing means canbe used, the most convenient and suitable technique is to place a heatshrinkable film such as polyethylene around the blocks and the palletfollowed by heating which causes the film 76 to shrink and snugly securethe blocks 77 to one another and to pallet 78. Although any conventionalpallet can be used for shipping the dense blocks, it is preferred to usea pulpable pallet, i.e. a pallet that can be broken down in the samemanner as the blocks are broken down at the point of use to act as aningredient in the resultant pulp. Pulpable pallets are well known andcan be made of cardboard or from a pulpy fibrous mass in a similarmanner to that used to make egg cartons. Asbestos fiber packaged in themanner shown in FIG. 7 can be shipped and stored in about one-half thespace required by the former packaging techniques.

At the point of use, the shrink film 76 is removed from the package andthe blocks 77 are fed into a block-breaker illustrated in FIGS. 5 and 6.Each block is fed into the opening 80 by placing the block on support 82and letting the block slide down plate 82 in the opening 80. The blockis contacted along its face by a plurality of rapidly moving chippingblades 86 mounted on a rotating drum 90 with pins 88. The drum 90 ismounted on an axle 92 supported by pillow block bearings 94 and isdriven by a suitable conventional drive means (not shown) by motor 98.The drum can be any suitable length but preferably is only slightlylonger than the longest dimension of the compressed asbestos block. Thechipping blades are spaced along the drum at frequent intervals eitherin a plurality of rows as illustrated or in a random pattern. Althoughfour rows of blades are preferred, more or less rows would also besuitable. The blades on any particular row can be staggered along thelength of the drum with respect to the blades on an adjacent row orrows. This block-breaker device is similar to the apparatus used tobreak the 50 PCF asbestos fiber units shipped in bags or boxes. It isnecessary, however, to strengthen the previously used disintegrater tomake it compatible with the high density blocks of the presentinvention. This strengthening is accomplished merely by using heavierguage material in the construction of the disintegrater particularly inthe drum 90, blades 86, pins 88, and retaining means 96.

Although the intermediate compaction device illustrated in FIG. 1 is thepreferred device for use in intermediately compacting the preliminarilycompacted damp asbestos fiber clumps to about 25 PCF prior to finalcompaction in the block press, other devices could be used forintermediate compaction. For example, a device comprising a series ofopposed rollers or a series of rollers opposing a moving flat surfacecould be used to compact the damp asbestos to a suitable intermediatedensity prior to final compaction.

What is claimed is:
 1. Apparatus for producing an asbestos block having a density of at least 90 PCF, said apparatus comprising:(a) mixing means for completely containing and mixing loose asbestos fibers and a small amount of liquid to produce a mixture in which the liquid is evenly distributed throughout the asbestos fiber and is present as no more than 8% by weight of fiber, said mixing means also preliminarily consolidating said mixture, and said mixing means also containing means for discharging the preliminarily consolidated mixture into consolidating means; (b) consolidating means disposed to receive said mixture discharged from said mixing means, said consolidating means further consolidating said mixture into an intermediately compacted body, said consolidating means including an extrusion device and a restrictive orifice, said consolidating means also containing means for discharging said intermediately compacted body into a press; and (c) a press disposed to receive said intermediately compacted body discharged from said consolidating means and including a mold chamber, said mold chamber having means for venting air from within said chamber during a compression stroke of said press, said press being capable of exerting sufficient compressive force on said intermediately compacted body to form said asbestos block of at least 90 PCF density.
 2. Apparatus as defined in claim 1 wherein said mixing means comprises an auger type mixer.
 3. Apparatus as defined in claim 2 further comprising nozzles for applying liquid to said asbestos fibers in said mixer.
 4. Apparatus as defined in claim 1 wherein said restrictive orifice is adjustable in size while said extrusion device is operating.
 5. Apparatus as defined in claim 1 wherein said venting means comprises openings in one or more walls of said chamber, said openings being covered on the inside of said chamber with a permeable material having openings therein that are substantially smaller than the openings in said chamber wall. 